The objective of this study is to determine the functions of a recently discovered and characterized group of cellular retinoid-binding proteins. We will examine the interactions of cellular binding proteins of the retina specific for retinol, 11-cis-retinal and retinoic acid, with enzymes, proteins and compartments known to be important in the metabolism of vitamin A in ocular tissues. Such interactions may lead to transfer of bound retinoid from a binding protein to an enzyme or protein, utilization of a bound form of the vitamin as a substrate in an enzymatic transformation (dehydrogenation, isomerization esterification, etc.), transport of retinol between intracellular compartments or neural retina and retinal pigment epithelium or perhaps the transfer of retinol from the serum retinol-binding protein to a cellular retinoid-binding protein. In addition the nature of the endogenous retinoids which purify with the retinoid-binding proteins will be examined in detail.